1. Field of the Invention
This invention relates to a hand tool having a claw and, more specifically, a hand tool having an extendable plunger disposed adjacent to the claw.
2. Background Information
Hand tools having claws include, but are not limited to, hammers, crowbars, and wrecking bars. Of these, hammers are the most common and well known and, hereinafter, it is understood that as used herein a “hammer” shall mean any hand tool having a claw. The claw, typically includes two fingers with a narrowing gap therebetween. The claw is disposed at one end of the hand tool, such as at the head of a hammer, and extends generally perpendicular to the longitudinal axis of the hand tool handle. The claw is, typically, slightly arcuate. The claw is used to pry nails and other elements away from a substrate. For example, a nail having a shaft and a head is disposed in a board. If the nail is not already loose, a user initially pries the nail out of the board using the distal tips of the claw. Once the nail head is spaced from the board, a user positions the nail shaft in the gap between the claw fingers and positions the head of the hammer against the board. The user then pivots the hammer in a plane extending through the axis of the gap in the claw and in a direction away from the claw. That is, the user pushes, or pulls, depending upon his position relative to the hammer, on the hammer handle in a direction away from the claw. As the head of the hammer pivots against the board, the claw engages the nail head. The claw and the nail then move away from the substrate while traveling through an arc. If a nail is generally short, for example, about an inch or two in length, such a motion will completely remove the nail from the board or remove enough of the nail so that the user may simply pull the nail free. That is, when the nail is inserted into the board, the nail creates a generally straight hole and is held in place by friction. When a nail is relatively short, the arcuate motion of the claw pulls the nail generally longitudinally until the friction with the board is reduced and the nail is pulled free.
There are, however, longer nails. Nails with an extended length may still be substantially disposed within the substrate and held by friction after the hammer has been pivoted. Also, where a long nail is made from a very rigid material, the nail may not bend as it is being pulled from the generally straight nail hole. In this instance, the head of the nail may be lifted above the claw causing the claw to simply slide over the shaft of the nail. From a mechanical perspective, the problem with this situation is that the pivot point of the hammer, as well as the path of travel of the claw, is below the head of the nail. Thus, one very old solution was to place a board, or other object, below the head of the hammer thereby placing the pivot point and the head of the nail in about the same plane. In this configuration, the pivoting motion of the hammer again caused the claw to engage and lift the nail head.
Rather than having a user find or carry an extra board, prior improvements incorporated a plunger into the tool head. That is, as shown in U.S. Pat. No. 540,697, a spring loaded plunger was disposed in the head of a hammer. The plunger was structured to extend along the axis of the hammer handle and was held in place by a release lever. The release lever included a lateral latch that engaged notches on the plunger. When the user actuated the release lever, the latch would disengage the notch and the spring would cause the plunger to extend from the top of the hammer head. The plunger positioned the hammer head a distance from the substrate, or board, and generally in the same plane as the head of the nail. The user could then pivot the hammer about the tip of the plunger. Disadvantages of this configuration included the cost and complexity of the release lever. Further, the release lever could accidentally release when the hammer was used to impact another object. That is, the release lever operated in a plane corresponding to the plane of the hammer head. Thus, when the hammer head impacted an object, e.g. a nail, the release lever could accidentally be actuated causing the plunger to extend.
Other hammers with plungers attempted to overcome some of these disadvantages by providing plungers that were held in place by threads, see e.g., U.S. Pat. Nos. 4,998,996 and 5,441,236. That is, the hammer head and/or handle included a threaded bearing and the plunger had a threaded outer surface. The plunger extended through the handle and an actuating knob was located at the bottom of the handle. By turning the knob, the plunger extended from the top of the hammer head. These designs, however, were difficult, or at least slow, to operate and required that the plunger extend through the entire handle. Such a design could not typically be used with a hammer having a unitary metal head and neck as the neck on such hammers were generally too thin to allow for the plunger.
Another design for a plunger included an inverted U-shaped cap disposed over the hammer head and coupled to the plunger, and, a tension spring drawing the plunger to a position within the hammer. See, U.S. Pat. Nos. 2,589,046 and 2,589,047. In this configuration, the user pulled the plunger into the extended position and rotated the U-shaped cap so that the tips of the cap engaged the hammer head. While this design could not be accidentally actuated, there were other problems. For example, the hammer head had to have pockets cut therein to accommodate the U-shaped cap as well as having a socket for the plunger cut into the handle. Because hammer heads are typically made from a hard metal, the cutting of the pockets is both time consuming and difficult.
There is, therefore, a need for a hand tool having a claw with a plunger that resists accidental actuation and which is easy to assemble.
There is a further need for a hand tool having a claw with a plunger that may be used with a metal hammer head having a unitary metal neck.